6 Python 2 and Python 3 applications using the standard
7 <a href="https://docs.python.org/3/howto/logging.html" class="ext"><code>logging</code> module</a>
8 can be traced by LTTng using the LTTng-UST Python agent.
10 Import the `lttngust` package in your Python application. For example:
19 logger = logging.getLogger('my-logger')
22 logger.debug('debug message')
23 logger.info('info message')
24 logger.warn('warn message')
25 logger.error('error message')
26 logger.critical('critical message')
30 if __name__ == '__main__':
34 Importing `lttngust` adds a logging handler which emits LTTng-UST
35 events. You do not need to get a special logger for tracing to work.
37 Use the `--python` option of the `lttng enable-event`,
38 `lttng disable-event`, and `lttng list` commands to target
39 Python applications. For example, here's how to enable the events
40 produced by the Python logger above:
43 lttng enable-event --python my-logger
46 Standard Python log levels are supported using the `PYTHON_` prefix.
47 For example, here's how to enable the warning (and more important)
48 events produced by the Python logger above:
51 lttng enable-event --python my-logger --loglevel PYTHON_WARNING
54 See [Enabling and disabling events](#doc-enabling-disabling-events) for
57 When loading, the LTTng-UST Python agent tries to register to the
58 [session daemon](#doc-lttng-sessiond). Note that the session daemon
59 needs to be started _before_ the Python application is started. If a
60 session daemon is found, the agent tries to register to it during
61 5 seconds, after which the application continues without LTTng
62 tracing support. This timeout value is overriden by the
63 `LTTNG_UST_PYTHON_REGISTER_TIMEOUT` environment variable (milliseconds).
65 If the session daemon stops while a registered Python application is
66 registered, the application retries to connect and register to a session
67 daemon every 3 seconds. This timeout value is overridden by the
68 `LTTNG_UST_PYTHON_REGISTER_RETRY_DELAY` environment variable.